<!-- HTML header for doxygen 1.9.6-->
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US">
<head>
<meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>
<meta http-equiv="X-UA-Compatible" content="IE=11"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title>CMSIS-RTOS2: Overview</title>
<link href="doxygen.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="dynsections.js"></script>
<script type="text/javascript" src="tabs.js"></script>
<script type="text/javascript" src="footer.js"></script>
<script type="text/javascript" src="navtree.js"></script>
<link href="navtree.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="resize.js"></script>
<script type="text/javascript" src="navtreedata.js"></script>
<script type="text/javascript" src="navtree.js"></script>
<link href="search/search.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="search/searchdata.js"></script>
<script type="text/javascript" src="search/search.js"></script>
<script type="text/javascript">
/* @license magnet:?xt=urn:btih:d3d9a9a6595521f9666a5e94cc830dab83b65699&amp;dn=expat.txt MIT */
  $(document).ready(function() { init_search(); });
/* @license-end */
</script>
<script type="text/javascript" src="darkmode_toggle.js"></script>
<link href="extra_stylesheet.css" rel="stylesheet" type="text/css"/>
<link href="extra_navtree.css" rel="stylesheet" type="text/css"/>
<link href="extra_search.css" rel="stylesheet" type="text/css"/>
<link href="extra_tabs.css" rel="stylesheet" type="text/css"/>
<link href="version.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="../../version.js"></script>
</head>
<body>
<div id="top"><!-- do not remove this div, it is closed by doxygen! -->
<div id="titlearea">
<table cellspacing="0" cellpadding="0">
 <tbody>
 <tr style="height: 55px;">
  <td id="projectlogo" style="padding: 1.5em;"><img alt="Logo" src="cmsis_logo_white_small.png"/></td>
  <td style="padding-left: 1em; padding-bottom: 1em;padding-top: 1em;">
   <div id="projectname">CMSIS-RTOS2
   &#160;<span id="projectnumber"><script type="text/javascript">
     <!--
     writeHeader.call(this);
     writeVersionDropdown.call(this, "CMSIS-RTOS2");
     //-->
    </script>
   </span>
   </div>
   <div id="projectbrief">Real-Time Operating System API</div>
  </td>
   <td>        <div id="MSearchBox" class="MSearchBoxInactive">
        <span class="left">
          <span id="MSearchSelect"                onmouseover="return searchBox.OnSearchSelectShow()"                onmouseout="return searchBox.OnSearchSelectHide()">&#160;</span>
          <input type="text" id="MSearchField" value="" placeholder="Search" accesskey="S"
               onfocus="searchBox.OnSearchFieldFocus(true)" 
               onblur="searchBox.OnSearchFieldFocus(false)" 
               onkeyup="searchBox.OnSearchFieldChange(event)"/>
          </span><span class="right">
            <a id="MSearchClose" href="javascript:searchBox.CloseResultsWindow()"><img id="MSearchCloseImg" border="0" src="search/close.svg" alt=""/></a>
          </span>
        </div>
</td>
  <!--END !PROJECT_NAME-->
 </tr>
 </tbody>
</table>
</div>
<!-- end header part -->
<div id="CMSISnav" class="tabs1">
  <ul class="tablist">
    <script type="text/javascript">
      writeComponentTabs.call(this);
    </script>
  </ul>
</div>
<script type="text/javascript">
  writeSubComponentTabs.call(this);
</script>
<!-- Generated by Doxygen 1.9.6 -->
<script type="text/javascript">
/* @license magnet:?xt=urn:btih:d3d9a9a6595521f9666a5e94cc830dab83b65699&amp;dn=expat.txt MIT */
var searchBox = new SearchBox("searchBox", "search/",'.html');
/* @license-end */
</script>
</div><!-- top -->
<div id="side-nav" class="ui-resizable side-nav-resizable">
  <div id="nav-tree">
    <div id="nav-tree-contents">
      <div id="nav-sync" class="sync"></div>
    </div>
  </div>
  <div id="splitbar" style="-moz-user-select:none;" 
       class="ui-resizable-handle">
  </div>
</div>
<script type="text/javascript">
/* @license magnet:?xt=urn:btih:d3d9a9a6595521f9666a5e94cc830dab83b65699&amp;dn=expat.txt MIT */
$(document).ready(function(){initNavTree('index.html',''); initResizable(); });
/* @license-end */
</script>
<div id="doc-content">
<!-- window showing the filter options -->
<div id="MSearchSelectWindow"
     onmouseover="return searchBox.OnSearchSelectShow()"
     onmouseout="return searchBox.OnSearchSelectHide()"
     onkeydown="return searchBox.OnSearchSelectKey(event)">
</div>

<!-- iframe showing the search results (closed by default) -->
<div id="MSearchResultsWindow">
<div id="MSearchResults">
<div class="SRPage">
<div id="SRIndex">
<div id="SRResults"></div>
<div class="SRStatus" id="Loading">Loading...</div>
<div class="SRStatus" id="Searching">Searching...</div>
<div class="SRStatus" id="NoMatches">No Matches</div>
</div>
</div>
</div>
</div>

<div><div class="header">
  <div class="headertitle"><div class="title">Overview </div></div>
</div><!--header-->
<div class="contents">
<div class="textblock"><p><a class="anchor" id="mainpage"></a> Modern embedded applications often need to concurrently execute multiple activities such as sensor readings, connectivity, machine-learning algorithms, graphics display and others. A real-time operating system (RTOS) equips users with necessary mechanisms that simplify implementation of complex programs and ensure their reliable operation with deterministic timing.</p>
<p><b>CMSIS-RTOS2</b> specifies a generic RTOS interface over real-time OS kernels running on Arm&reg; Cortex&reg; processor-based devices. Applications and middleware components can <a class="el" href="usingOS2.html">use CMSIS_RTOS2 API</a> for better code reuse and simpler integration in various software ecosystems.</p>
<p>CMSIS-RTOS2 also specifies a standard <a class="el" href="group__CMSIS__RTOS__TickAPI.html">OS Tick interface</a> for use by RTOS kernels. It provides several OS tick implementations for simple kernel porting to different Cortex-M and Cortex-A processors.</p>
<div class="image">
<img src="cmsis_rtos2_overview.png" alt=""/>
<div class="caption">
CMSIS-RTOS2 interface</div></div>
    <h1><a class="anchor" id="rtos2_benefits"></a>
Benefits</h1>
<p>CMSIS-RTOS2 provides great benefits to the embedded developers and software vendors:</p>
<ul>
<li>The CMSIS-RTOS2 API covers all common services expected from a modern RTOS kernel for efficient thread management, inter-thread communication, timing control and others. See <a class="el" href="usingOS2.html#rtos2_functionalities">Functionality overview</a> for details.</li>
<li>The unified API increases developers' productivity and reduces learning efforts. It makes the software components reusable across different software stacks.</li>
<li>The API enables use of advanced CPU features by RTOS and application, such as secure/non-secure execution with TrustZone, multi-core operation, access protection with MPU, and others.</li>
<li>The C interface is binary compliant with the <a href="https://github.com/ARM-software/abi-aa/">Application Binary Interface (ABI) for Arm architecture</a> and enables inter-operation between various toolchains.</li>
<li><a class="el" href="rtosValidation.html">RTOS Validation Suite</a> provides a set of tests to verify compatibility to CMSIS-RTOS2 API definitions.</li>
<li>CMSIS-RTOS2 is well adopted by the industry, has many years of continuous improvements and commitment for future developments.</li>
</ul>
<blockquote class="doxtable">
<p>&zwj;<b>Note</b></p><ul>
<li>The CMSIS-RTOS2 defines a minimum feature set. It's architecture allows to use advanced vendor-specific features directly as well. </li>
</ul>
</blockquote>
<h1><a class="anchor" id="rtos2_kernels"></a>
Supported RTOS kernels</h1>
<p>Many popular RTOS kernels include support for CMSIS-RTOS2 API:</p>
<p><b>CMSIS-RTX</b> (or Keil RTX5): provides most complete support for CMSIS-RTOS2 API and uses it as native interface. For more information see:</p>
<ul>
<li><a href="https://github.com/ARM-software/CMSIS-RTX">CMSIS-RTX GitHub repository</a></li>
<li><a href="https://arm-software.github.io/CMSIS-RTX/">CMSIS-RTX documentation</a></li>
<li><a href="https://www.keil.arm.com/packs/cmsis-rtx-arm/versions/">CMSIS-RTX pack</a></li>
</ul>
<p><b>FreeRTOS</b> : this popular RTOS kernel is enabled with CMSIS-RTOS2 API in the <em>CMSIS-FreeRTOS</em> variant. To learn more see:</p>
<ul>
<li><a href="https://github.com/ARM-software/CMSIS-FreeRTOS">CMSIS-FreeRTOS GitHub repository</a></li>
<li><a href="https://arm-software.github.io/CMSIS-FreeRTOS/">CMSIS-FreeRTOS documentation</a></li>
<li><a href="https://www.keil.arm.com/packs/cmsis-freertos-arm/versions/">CMSIS-FreeRTOS pack</a></li>
</ul>
<p><b>Zephyr RTOS</b>: is developed under governance of Linux Foundation and includes CMSIS-RTOS2 API support. See more at:</p>
<ul>
<li><a href="https://github.com/zephyrproject-rtos/zephyr">Zephyr GitHub repository</a>, see folder <em>subsys/portability/cmsis_rtos_v2/</em></li>
<li><a href="https://docs.zephyrproject.org/latest/services/portability/cmsis_rtos_v2.html">Zephyr documentation about CMSIS-RTOS2 support</a></li>
</ul>
<p><b>embOS</b>: is a preemptive RTOS designed by Segger, and provides support for CMSIS-RTOS2 API.</p>
<ul>
<li><a href="https://wiki.segger.com/Using_embOS_in_CMSIS-Pack_projects">Using embOS in CMSIS-Pack projects</a></li>
<li><a href="https://www.keil.arm.com/packs/cmsis-embos-segger/versions/">CMSIS-embOS pack</a></li>
</ul>
<p><b>Azure ThreadX RTOS for STM32</b>: is an integration of Azure RTOS into STM32 middleware provided by STMicroelectronics.</p>
<ul>
<li><a href="https://wiki.st.com/stm32mcu/wiki/Introduction_to_THREADX#CMSIS-RTOS_API_Support">CMSIS-RTOS API support in ThreadX for STM32</a></li>
</ul>
<p><b>Micrium OS</b> is developed and maintained by Silicon Labs.</p>
<ul>
<li><a href="https://www.silabs.com/developers/rtos">Micrium OS overview and comparison</a></li>
</ul>
<h1><a class="anchor" id="rtos2_access"></a>
Access to CMSIS-RTOS2</h1>
<p>CMSIS-RTOS2 and OS Tick intefaces are actively maintained in the <a href="https://github.com/ARM-software/CMSIS_6"><b>CMSIS 6 GitHub repository</b></a> and provided as part of the <a href="../General/cmsis_pack.html"><b>CMSIS Software Pack</b></a>.</p>
<p>The following files and directories relevant to CMSIS-RTOS2 are present in the <b>ARM::CMSIS</b> Pack:</p>
<table class="markdownTable">
<tr class="markdownTableHead">
<th class="markdownTableHeadLeft">File/Directory   </th><th class="markdownTableHeadLeft">Content    </th></tr>
<tr class="markdownTableRowOdd">
<td class="markdownTableBodyLeft">📂 CMSIS   </td><td class="markdownTableBodyLeft">CMSIS Base software components folder    </td></tr>
<tr class="markdownTableRowEven">
<td class="markdownTableBodyLeft">┣ 📂 Documentation/html/RTOS2   </td><td class="markdownTableBodyLeft">A local copy of this CMSIS-RTOS2 documentation    </td></tr>
<tr class="markdownTableRowOdd">
<td class="markdownTableBodyLeft">┗ 📂 RTOS2   </td><td class="markdownTableBodyLeft">CMSIS-RTOS2 API header files and OS tick implementations    </td></tr>
<tr class="markdownTableRowEven">
<td class="markdownTableBodyLeft">&emsp;&#160; ┣ 📂 Include   </td><td class="markdownTableBodyLeft">API header files    </td></tr>
<tr class="markdownTableRowOdd">
<td class="markdownTableBodyLeft">&emsp;&emsp;&#160; ┣ 📄 cmsis_os2.h   </td><td class="markdownTableBodyLeft"><a class="el" href="usingOS2.html#cmsis_os2_h">cmsis_os2.h API header file</a>    </td></tr>
<tr class="markdownTableRowEven">
<td class="markdownTableBodyLeft">&emsp;&emsp;&#160; ┗ 📄 os_tick.h   </td><td class="markdownTableBodyLeft"><a class="el" href="group__CMSIS__RTOS__TickAPI.html">OS Tick API</a> header file    </td></tr>
<tr class="markdownTableRowOdd">
<td class="markdownTableBodyLeft">&emsp;&#160; ┗ 📂 Source   </td><td class="markdownTableBodyLeft">OS tick implementations    </td></tr>
<tr class="markdownTableRowEven">
<td class="markdownTableBodyLeft">&emsp;&emsp;&#160; ┣ 📄 os_systick.c   </td><td class="markdownTableBodyLeft">OS tick implementation using Cortex-M SysTick timer    </td></tr>
<tr class="markdownTableRowOdd">
<td class="markdownTableBodyLeft">&emsp;&emsp;&#160; ┣ 📄 os_tick_gtim.c   </td><td class="markdownTableBodyLeft">OS tick implementation using Cortex-A Generic Timer    </td></tr>
<tr class="markdownTableRowEven">
<td class="markdownTableBodyLeft">&emsp;&emsp;&#160; ┗ 📄 os_tick_ptim.c   </td><td class="markdownTableBodyLeft">OS tick implementation using Cortex-A Private Timer   </td></tr>
</table>
</div></div><!-- PageDoc -->
</div><!-- contents -->
</div><!-- doc-content -->
<!-- start footer part -->
<div id="nav-path" class="navpath"><!-- id is needed for treeview function! -->
  <ul>
    <li class="footer">
      <script type="text/javascript">
        <!--
        writeFooter.call(this);
        //-->
      </script> 
    </li>
  </ul>
</div>
</body>
</html>
